In an information-centric network (ICN), communication is not based on packets that are “sent from” and “destined to” hosts or host interface addresses. In ICN, requestors send requests to the network, asking for named data objects (NDOs) that have been published before and that are available in one or many copies in the network. The network elements, e.g. switches or nodes, that receive a request—unless they have a local copy in their cache—typically have to decide where to forward the request to, for example which interface to use for forwarding the request. Typically a network switch or network node can participate in a routing protocol that helps to distribute this information, or a network switch or network node can employ a Name Resolution Service (NRS) that can map NDOs to locators in underlying networks, for example an IP network.
Once a request has been forwarded and reached the destination, e.g., a NDO copy in a cache, a corresponding response message, i.e., the NDO or a locator, has to be relayed back to the requestor, possibly passing one or more on-path caches that can cache the objects in order to satisfy future requests from their cache. This return path can be determined in different ways: For example network elements can maintain state or they can obtain some information from data structure inside messages, such as a label stack.
A survey of information-centric networking is obtainable from Ahlgren, B.; Dannewitz, C.; Imbrenda, C.; Kutscher, D.; Ohlman, B., “A survey of information-centric networking,” Communications Magazine, IEEE, vol. 50, no. 7, pp. 26,36, July 2012, doi: 10.1109/MCOM.2012.6231276, URL: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6231276
The basic idea of software-defined networking (SDN) is to separate network control-plane logic from data-plane forwarding. This means breaking today's feature-rich network elements, e.g. switches, nodes or routers, into dumb forwarding elements and complex network controllers. SDN relies on the concept of providing an application programming interface (API) or protocol for packet forwarding devices such as switches, nodes and routers, which allows programmability of network elements and entire networks. An example for such a controller to switch protocol is OpenFlow, see OpenFlow Switch Specification, Version 1.0.0 (Wire Protocol 0x01), Dec. 31, 2009. http://www.openflow.org/documents/openflow-spec-v1.0.0.pdf.
Information-centric networking approaches, such as Content Centric Networking (CCN), or Network of Information (NetInf), follow the basic principle of addressing content objects, NDOs, and not hosts or end-points. One often mentioned advantage in ICN is “request aggregation”. Request aggregation is the concept to avoid forwarding subsequent requests for the same NDO arriving at the same ICN node or switch, so that the request and the NDO are transmitted only once over the path between that node or switch and the content source. For reference, see also FIG. 1 which is showing a per-node request aggregation. Concretely, FIG. 1 is showing three different points in time, where requests R1, R2 and R3 are performed from different requestors. There is requested a content A which is provided within a source S. The content A shall be transmitted to hosts H1, H2 and H3 according to the indications by arrows within FIG. 1, right part. Nodes N1 to N6 are provided within the shown ICN structure. The left part of FIG. 1 is showing the request R1 for the content A. This request R1 is transmitted from N1 to N6 and the source S as shown within the left and middle parts of FIG. 1. Within this middle part of FIG. 1 a further request R3 is directed to N1 and is aggregated and delayed by node N1. A further request R2 directed to node N2 will be transmitted to N6 and the source S. As obtainable from the right part of FIG. 1 the content A is transmitted two times on two ways from S to N1 and from S to N2 for provision to hosts H1, H2 and H3.
For request aggregation in ICN, a node or switch delays the forwarding of subsequent requests for the same NDO, as the responses to the first request are expected to pass by and will then serve both or all requests. Per-node request aggregation is well known for ICN.